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J. H. MELLOY AND W. OWEN. MACHINE TOOL EMPLOYING WORM GEARING FOR DIVIDING PURPOSES..

APPLICATION FILED IAN. I9, I918- Patented Sept. 23; 1919.

4 SHEETS-SHEET II J. H. MELLOY AND W. OWEN. MACHINE TOOL EMPLOYING WORM GEARING FOR DIVIDING PURPOSES.

APPLICATION FILED JAN. I9. I918- PatentedSept, 23,1919.

SHEETS-SHiiT 2- Arr? 1. H. MELLOY AND w. OWEN; I MACHlNE TOOL EMPLOYING WORM GEARING FOR DIVIDING PURPOSES.

APPLICATION FILED IAN- l9. SIB. v 1 ,3 1 6, 96 6 Patented Sept. 23, 1919.

4 SHEETSSHEET 3- J. H. MELLOY AND W. OWEN.

MACHINE TOOL EMPLOYING WORM GEARING FOR DIVIDING PURPOSES. APPLICATION FILED JAN. 19. IS H8.

1 ,3 1 6,966 Patented Sept. 23, 1919.

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THE coLumnlA PLANOORAPM c0 WASHINGTON. l v c.

AM HENRY ME L Y Ann-WILLIE OWEN,

0F ONE-THIRD TOWILLIAJM MUIR AND CQMRAN IM TED:

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F M N ESTER, NGL ND, ASSIGN R Q M NC E TER, ENG- MACHINE-TOOL EMPLOYING WORM-GEABING FOB, DIVIDING PURPOSES,

Specification of Letters Patent.

Pa nt d Sep 23, 1919- Application filed January 19. 1918. Serial No. 212,749.

To all whom it may concern:

Be it known that we, JAMES LOY and WILLIE Owen, King of Great Britain, residing at Britannia lVorks, Sherbourne street, Manchester, in the county of Lancaster, England, have invented new and useful Improvements in Machine-Tools Employing orin-Gearing for Dividing Purposes, of which the following is a specification.

This invention relates to improvements in gear cutting machines and other machine tools employing worm gearing for dividing purposes, and consists essentially in the provision ofmeans for compensating during r0- tation for the wear of the worm in order to prevent such wear affecting the accuracy ofthe work under production.

The necessity for compensation arises from first, the wear of the worm tooth during cutting, resulting in a difierent relative position of the teeth of the worm wheel and worm affecting the angle of the tooth in the work produced, and, secondly, the accumulation of such wear resulting in backlash.

We further embody, as a feature of our invention, the provision of means for indicating the amount of wear.

In gear hobbing machines and machines of a like nature, the work is usually rotated by means of a worm and worm wheel and it is more particularly to this type of machine and to the worm mentioned that this invention is intended to apply.

Previously, in such mac lines, the worm has not been fitted with any means to pre vent the effects of the wear being produced in the work nor have means been provided to indicate the amount of such wear during rotation nor has it been possible even to remove backlash during rotation, the only known refinement in this direction being the arrangement of the worm in such a manner that the backlash can be taken out, but only when the machine is at rest and such HENRY MEL- periodic removal of the backlashmerely re moves shake and is not intended to, and does not. prevent the effect of the wear being produced on the work.

An embodiment of the invention is illustrated in the accompanying four sheets of drawings in which-- Figure 1 is a side elevation. Fig. 2 am both subjects of the 7 is supposed to be applied to the dividing worm of a gear hobbing machine similar to that described and claimed in the specification to the British patent of Wm. Muir and Company, Limited, and Melloys N0. 6595 The enveloping bracket a is carried upon the bed of such machine, and the tableb,

to which is attached the worm wheel, carries the work which is being produced. The shaft 0 which is driven in the usual manner, has keyed upon it the worm cl which rotates the worm wheel and table I). To the end of this worm d is fitted a shorter section of similar worm e keyed to the same shaft 0 and fitted in such a way that the thread of the worm is not cut through in a manner to leave a feather edge but the section is cut round in a spiral to follow the thread, the ioints of the thread being across the line f-g, Fig. 1. The end of this section worm c is screwed, and a nut h fitted upon it. Attached to the worm section e at y is a strong coiled spring is the other end of which is attached to the nut h. This spring is placed upon the worm section 6 and the nut h in such a manner as to exert a turning movement upon the nut h in' a direction tendingto wind the nut it off the worm e and sufficient tension is put into the spring to overcome the friction of the threads of the nut h on the worm e. The nut h abuts upon a plate Z which thrusts on to ball washers m bearing against the boss of the bracket a. The otherend of the worm d also thrusts upon ball washers 0. The whole of this mechanism is carried in the circular bracket or casingn which is screwed on its periphery and fits into the bracket a, which is also screwed as shown at p, Fig. 3. Fitted to the bracket a carried by a pin g, Fig. 4,

protruding through an opening in the cir-' cular bracket n is a lever 1'1 the end of which presses lightly against theside of the thread in section, Fig. 3, and shown also in Fig. 4:.

To the end of the extension arm of the lever 1" is fitteda screw it with an electrical point 7 contact which can make contact with a corresponding screw 1) carried on a projection from the bracket at. These two contactsare connected in the usual way with a battery ,andbell or other signal, not shown. At one portion in the circularbracket a, worm with a worm w Fig. 2, carried in thezbody of the bracket a and actuated by a hand wheel y. Fitted to the hand wheel'y ,is a

or loose index plate 2 which can be adjusted on the hand wheel 2 but locked to it when required by means of a pinching screw. 3/. -.-An

indicator or pointer 4 pro ecting. on the index ring a is carriedon a projection from the bracketa.

The. operationof the mechanism is as follows V The shaft 0 is rotated in such a manner as to rotate the worm wheel and table 5 Lin-the direction shown by the arrow 1, Fig.

3, thus insuring that the pressure on the worm threads is coming upon that" side which the lever r is pressing upon and also that the main thrust of the worm is coming upon the ball washers 0;

7 Clearance is cutbetweenthe two sections of worms d and 6 so as to allow the threads of the worm sectionc to come in contact with the opposite'sides of the teeth of the worm wheel I) which are being acted upon by the worm (Z.- During the rotation of the worm thus ringing a hell, not shown, or giving any wheel teeth w, Flg. 3, are cut whichgear the lever 1' will be pulled through that slot by means of the spring 8 allowing the lever 1' to swing in one direction slowly through a v the arc indicated and to drop back quickly under the influence of the spring. It is obvious that as the threads ofth e worm d I other suitable signal. The attention of-the attendant is by this means drawn to the mechanism and the hand wheel y is rotated .by the attendant the required amount and bycmeans of the worm m and. the worm teeth w cut in the circular bracket n this bracket is rotated on thecenterofthe worm d and due to its being Screwedin the bracket a is moved endwise in the direction of the arrow 2, Fig. 8, so as-to bring the side 1 of the tooth of the worm cl again into/the original position relatively to theteeth; of

v the worm wheel b. sflightest wear of the worm d is brought instantly tothe notice of the attendant, and that wear: immediately compensated for, thus ;.preventing the effects of such wear b'eing produced on the worm wheel 6 and conse- 7 tlon; consequently during any time after the d any wear which takes place upon the sides from the worm e and in the ordinary condition of things backlash would develop.

The coiled spring 76 now comes into action of the thread of that worm allowsthe teeth of the worm wheel I) to move relatively away of mechanism to con and rotates the nut it upon the worm section, I

thus causing the said section to follow up I the relative movement of the teeth of the worm wheel 5 to the worm section 6, and

i 7 and 8, is connected quently upon the work carried on the table. The index plate a is set to zero opposite the pointer 3/ at the commencement of rota- In this manner, the

adjustment of the hand wheel y for compensating wear, the reading on the index plate a will be an indication of the total amount of wear since the commencement of rotation.

The foregoing'illustrates an arrangement pensate for wear by hand only.

Figs; 5, 6, 7 and 8 illustrate a method of compensating for wear automatically.

In this case the oscillating lever r, Figs.-

to a ratchet lever 3 'which can gear with a ratchet wheel 4 [keyed upon the worm shaft 5. The ratchet so slightly closing the clearance space be-- tween the two sectioned and e of the worm thus keeping the threads of the worm e I i always-in contact with the opposite sides ofithe .teeth of. the-worm wheel 6; the-two sides'of-the. worm wheel I) are therefore always heldvthe driving side by the large thus automatically developing.

. -f During the rotation of the; worm (Z the :lever rbeing pressed upon the working sides of the threads of this worm by the spring 8,

will move in the are indicated in Fig. 3, and as the slot t in the worm 0? comes around lever 3 is loosely mountedupon the bossoof the ratchet wheel.

As the ratchet lever 3 oscillates under the influence of the oscillating leverr, the ratchet catch 6 on the lever oscillates idly along the back of the teeth of the ratchet wheel 4 thus imparting no motion to the ratchet wheel but as the arc of oscillation'of'the ratchetrlever 3' is moved slightly, due as before mentioned to e the wear on the threads of the wound, the

ratchet catch 6 comes into gear with the teeth on the ratchet wheel which is then ro-,

tated one tooth; so imparting motion to the vertical shaft 5 and consequently as described to the worm d thus again automatically bringing the threads of the worm d back into their original position relatively to the teeth of the wheel and so compensatin for wear.

hat we claim as our invention and desire to secure by Letters Patent of the United States is 1. In a machine tool employing worm gearing for dividing purposes, the combination with means actuated during rotation to compensate for the wear of the worm and means which during the rotation of the worm wheel automatically take up and compensate for backlash, of indicating means whereby it is rendered possible to observe at any moment during the rotation of the worm the amount of wear since the commencement of rotation.

2. In a machine tool, in combination, a combined table and worm wheel; a worm formed in two sections d and 0 with a clearance space between them; a nut h mounted on the worm section a and rotated by a coiled spring is; a lever biased to a redetermined positlon, a contact controlled by said lever, and electrical means controlled by said contact for indicating the wear of said worm.

3. In a machine tool, in combination, a combined table and worm wheel; a worm formed in two sections d and 6 with a clearance space between them; a nut 7t mounted on the worm section 6 and rotated by a coiled spring k; a Worm shaft, a ratchet gear keyed to said shaft, and an oscillating lever r operatively connected to said ratchet gear for actuating the latter, whereby the movements of said shaft are transmitted to the worm d to compensate for wear.

4. A machine of the character described, comprising a worm wheel and a worm meshing therewith, and means actuated during rotation of the worm to compensate for the wear of the worm.

5. A machine of the character described, comprising a worm wheel and a worm meshing therewith, means actuated during rotation of the worm to compensate for the wear of the worm, and means actuated during rotation of the worm for automatically compensating for backlash of the worm wheel.

6. A machine of the character described, comprising a shaft, a worm fixed to the shaft, a second worm keyed to said shaft, a worm wheel meshing with said worms,

means for automatically actuating the sec-' ond worm to prevent backlashing of the worm wheel, and means actuated by the first worm to compensate for the Wear of the worm.

7. A machine of the character described, comprising a shaft, a worm fixed to the shaft, a second worm keyed to said shaft, a worm wheel meshing with said worms, means for automatically actuating the second Worm to prevent backlashing of the worm wheel, means actuated by the first worm to compensate for the wear of the worm, and means actuated by the first worm for indicating the amount of wear thereof.

8. A machine of the character described, comprising a shaft, a worm fixed to the shaft, a second worm keyed to said shaft, a worm wheel meshing with said Worms, means for automatically actuating the second Worm to prevent backlashing of the worm wheel, means actuated by the first worm to compensate for the wear of the worm, and signaling means controllable by the first worm..

9. A machine of the character described, comprising a shaft, a worm fixed to the shaft, a second worm keyed to said shaft,

a worm wheel meshing with said Worms, means for automatically actuating the second worm to prevent backlashing of the worm wheel, means actuated by the first worm to compensate for the wear of the worm, a lever, means formed on the first worm for rocking said lever during rotation thereof, and a contact controlled by said lever.

10. A machine of the character described, comprising a worm wheel and a worm meshing therewith, means actuated during rotation of the worm to compensate for the wear of the worm, said means comprising a bracket rotatable upon said shaft, and means for moving said bracket longitudinally of said shaft, whereby said worm will be moved to compensate for the wear between said. worm and said worm wheel.

In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses.

JAMES HENRY MELLOY WILLIE OWEN. Witnesses:

S. W. GILLETT,

I HERBERT ROWLAND ABBEY.

copies of this patent may be obtained for five cents each, by addressing the "Commissioner of Patents, Washington, D. 0. 

